The present invention relates to a traction slip control method for an automotive vehicle wherein a traction slip control phase for a respective drive wheel is activated by way of a control strategy when the traction slip of said wheel exceeds a predeterminable slip threshold value (Ssw).
Further, the present invention relates to a control circuit for controlling the driving stability of a vehicle wherein defining input quantities are sensed and processed for fixing a course so that a traction slip control operation can be carried out by influencing the transmission of engine torques to individual wheels.
A generic method and a generic device are known from the book of M. Burckhard, xe2x80x98Fahrwerktechnik; Radschlupf-Regelsystemexe2x80x99, Vogel-Buchverlag, 1993.
During traction slip control operations in sharp curves (hairpin turns), the engine torque is controlled to a low level due to the relief of the curve-inward drive wheel in connection with sensitive slip control thresholds. In the course of further acceleration out of the curve, especially at high coefficients of friction where the wheel slip stabilizes again quickly, due to driving stability, a lack in traction will occur, which traction is possible and desired by the driver.
An object of the present invention is to improve upon a generic method so that an increase in traction is achieved during cornering, especially in an acceleration process that takes place during cornering.
According to the present invention, this object is achieved in that a generic method is performed so that a reference transverse acceleration is determined for a cornering maneuver to be expected, that an actual transverse acceleration is determined, that a difference between the reference transverse acceleration ay-ref and the actual transverse acceleration ay-ist is calculated, and it is determined whether the amount of the difference exceeds a limit value, and wherein in the case that the amount of the difference exceeds the limit value, the control strategy is modified so that a higher torque can be achieved at least on two wheels than in the case that the amount of the difference does not exceed the limit value.
Besides, the present invention arranges for a generic control circuit to be so configured that the control circuit comprises at least one means for determining and/or storing a reference transverse acceleration and a comparator, wherein the comparator compares the reference transverse acceleration ay-ref with a determined actual transverse acceleration.
Thus, the present invention discloses determining by a comparison between a reference transverse acceleration and an actual transverse acceleration whether a transmission of engine torques to the individual wheels shall be influenced.
An advantageous implementation of the present method, or an expedient embodiment of the device is characterized in thatxe2x80x94when the amount of the difference exceeds the limit valuexe2x80x94a higher torque is achieved on all driven wheels.
To enhance the reliability it is suitable that the reference transverse acceleration is determined in dependence on the actual transverse acceleration.
Further, it is favorable that the torque is only increased when the reference transverse acceleration (ay-ref) is higher than a threshold value K2.
A particularly suitable embodiment of the method and the device is characterized in that for at least one wheel of the vehicle an engine torque is determined which can maximally be used on this wheel.
It is especially advantageous that for all driven wheels of the vehicle that engine torque is determined which can maximally be used on them.
For a further increase in driving stability, it is suitable that the maximally utilizable engine torque is determined by a slip requirement of at least one inward wheel.
A favorable implementation of the present method or embodiment of the device, respectively, is characterized in that an increase of the torque achieved on the wheels is carried out only when slip signals do not exceed a defined threshold value.